Overview
The following sections illustrate how to perform:
A series of moves treated as a Series of Discrete Profiles
A series of trapezoidal or profile position special velocity moves treated as One Continuous Profile
7: Profile Position, Velocity, and Torque Mode Operation CANopen Programmer’s Manual
Series of Discrete Profiles
This diagram illustrates how to implement a series of moves as a series of discrete profiles.
action or query done by amplifier
action or query done by CANopen master
Set Control Word bit 4 (to 1).
Amplifier sees bit 4 0-1 transition;
Clear Control Word bit 4 (to 0).
Am plifier clears bit 12 (to 0).
When target position is reached, am plifier sets bit 10
of Status Word (to 1).
Set move parameters.
Set profile type to 0 for trapezoid; 1 for s-curve.
Clear Control Word bit 4 (to 0).
0
1
Amplifier sets Status Word bit 12 (to 1).
1. Control Word bit 5 is “change set immediately.”
Clearing it tells the amplifier to treat a series of moves as a series of discrete profiles.
2. Move Parameters are described on page 193.
3. Control Word bit 4 is “new setpoint.” It needs to be 0 because the move is triggered by a 0->1 transition.
4. Status Word bit 10 is “target reached.” Value is 0 when move is in progress; 1 when move is finished.
5. Value of 1 indicates that valid data has been sent to amplifier and new move should begin.
6. Amplifier must detect 0-1 transition to begin move.
7. Control word bit 6: value 0 causes absolute move;
value 1 causes relative move.
8. Status Word bit 13 is “setpoint acknowledge.” A value of 1 indicates the amplifier has received a setpoint and has started the move.
9. Control Word bit 4 is “new setpoint.” It needs to be 0 to allow the next move is triggered by a
0->1 transition. Also, the 1->0 transition causes the amplifier to clear bit 13.
10. Amplifier detects 0->1 transition of Control Word bit 4 and clears bit 13 in response.
When the motor reaches the target position, the amplifier sets Status Word bit 10 (“target reached”) to 1.
11. CANopen master returns to step 2 if there are more moves to complete; otherwise, the series of moves is finished.
CANopen Programmer’s Manual 7: Profile Position, Velocity, and Torque Mode Operation
Copley Controls 197
One Continuous Profile
This diagram illustrates how to implement a series of moves as one continuous profile.
Control Word
bit 4
Set Control Word bits 4 and 5 (to 1).
Am plifier sees bit 4 0-1 transition; sees that bit 5 is set;
copies buffered m ove to active registers.
Clear Control Word bit 4 (to 0).
Amplifier clears Status Word bit 12 (to 0).
Set move parameters;
Set profile type to 0 (for trapezoidal move).
Clear Control Word bit 4 (to 0).
0
1
Amplifier Status Word bit 12 (to 1).
action or query done by amplifier
action or query done by CANopen master
1. Move Parameters are described on page 193. This type of move is only supported as a trapezoidal profile.
2. Control Word bit 4 is “new setpoint.” It needs to be 0 because the move will be triggered by a 0->1 transition.
3. Bit 4, value of 1 indicates that valid data has been sent to amplifier and new move should begin.
Bit 5 is “change set immediately.” A value of 1 tells the amplifier to update the current profile immediately by copying the contents of the move buffer to the active registers (without waiting for move to finish).
4. Amplifier must detect bit 4 0-1 transition to begin move. Bit 5 value 1 allows immediate update.
5. Control word bit 6: value 0 causes absolute move; value 1 causes relative move.
6. Status Word bit 13 is “setpoint acknowledge.” A value of 1 indicates the amplifier has received a setpoint and has started the move.
7. Control Word bit 4 is “new setpoint.” It needs to be 0 to allow the next move will be triggered by a 0->1 transition. Also, the 1->0 transition causes the amplifier to clear bit 13.
8. Amplifier detects 0->1 transition of Control Word bit 4 and clears bit 13 in response.
When the motor reaches the target position, the amplifier sets Status Word bit 10 (“target reached”) to 1.
9. CANopen master returns to step 1 if there are more moves to complete; otherwise, the series of moves is finished.
7: Profile Position, Velocity, and Torque Mode Operation CANopen Programmer’s Manual
Trapezoidal vs. S-Curve Profile: Some Design Considerations
Difference Between Trapezoidal and S-Curve Profiles
Here is a review of the differences between trajectory and S-curve profiles, and some design considerations indicated by those differences:
Trapezoidal Profile S-Curve Profile Design Considerations Unlimited jerk, operation not as
smooth.
Limited jerk, smoother operation. If the application cannot tolerate jerk, use S-curve.
If the application can tolerate jerk, other features available exclusively in trapezoidal profile may indicate its use.
Supports separate acceleration and deceleration rates.
Does not support separate
deceleration rate; uses acceleration rate for acceleration and deceleration.
If a separate deceleration rate is critical, the trapezoidal profile is indicated.
Supports modification of current move parameters during current move, allowing the execution of a series of moves as a continuous profile.
Does not support modification of current move. A series of moves requires a series of discrete profiles.
If current move modification is critical, the trapezoidal profile is indicated.
Generally requires less torque than the S-curve profile to complete an equal move in equal time.
Generally requires more torque than a trapezoidal profile to complete an equal move in equal time, to make up for time sacrificed for gentler starts and stops.
Designers switching a profile from trapezoidal to S-curve or lowering the value of Trajectory Jerk Limit (index 0x2121, p. 202) might notice some slowing. A higher Profile Acceleration can be applied to compensate, but watch out for amplifier and motor limits.
CANopen Programmer’s Manual 7: Profile Position, Velocity, and Torque Mode Operation
Copley Controls 199